(no subject)

Hiranya Roychowdhury hroychow at NMSU.EDU
Fri Nov 15 11:55:10 EST 1996


At 02:54 PM 11/15/96 +0100, Haralt Leiter wrote:
>Hi everybody !
>
>I=B4m a poor PhD Student (my supervisor hasn=B4t paid me) purifying a
>fucosyltransferase with an estimated (SDS-PAGE) molecular weight of at
>least 50kDa. During ultrafiltration the entire enzyme-activity passes
>through the membrane (cutoff 30000). Has anybody observed a similar
>effect or can offer a reasonable explanation ?
>I use a 25mM Tris/HCl pH7,3
>	0,1% Triton X-100
>	10% Glycerol
>	0,02% NaN3    buffer and the applied protein solution contains several
>hundreds of micograms.
>Thanks for any answers in advance
>
>Haralt
>
>BTW, I have already tried membranes of different companies
>
>
Just a possibility:
A polypeptide showing an Mr or 50kDa on SDS-PAGE may very well have a
physical Skokes radius equivalent to 30kDa (or slightly less)  in its native
form. Also, check the retention using conventional dialysis using membranes
of 30k (and less) cut-offs.=20

Dr. Hiranya Sankar Roychowdhury
Plant Genetic Engineering Lab.
New Mexico State University
Las Cruces, NM 88003
Ph. (505) 646-5785
hroychow at nmsu.edu




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